Biology Reference
In-Depth Information
Three denitrifying strains of bacteria ( Pseudomonas aeruginosa, Paracoccus
denitrifi cans , and Pseudomonas sp.) isolated from a fl uidised bed reactor were
tested for their ability to remove nitrate and phosphate in a recirculating
fi sh culture system. The treatment system consisted of a digestion basin,
a denitrifying fl uidised bed reactor and a nitrifying trickling fi lter. After
210 d of treatment inorganic nitrogen and phosphate concentrations
(obtained from the trickling fi lter basin) did not accumulate ( Figs. 9.4, 9.5 ).
More than 90% of phosphorus was retained within the organic matter of
the trickling fi lter. The organic material obtained from the fl uidised bed
reactor was rich in phosphorus up to 11.8% of dry weight, while in the
trickling fi lter 1.9% of dry weight. In addition, nitrate was produced in
the trickling fi lter, removed in the fl uidised bed reactor and removed or
produced in the digestion basin (Barak and van Rijn, 2000).
Treatment methods based on the use of various microorganisms for
aquaculture waste remediation (parameters, quality control and results)
are presented in Table 9.5.
Techniques Based on the Use of Microorganisms for Aquaculture Waste
Three ensiling experiments (two small silo and one large silo) of crab
waste and wheat straw treated with different additives were conducted
by Abazinge et al. (1993). In the fi rst small silo experiment crab waste and
wheat straw (1:1, wet basis) were ensiled with 0-20% dry molasses, 0-0.1%
microbial inoculant, and 0-5.4% phosphoric acid (H 3 PO 4 ), and 20% water
(Experiment 1), while in the second small silo experiment 10-20% dry
molasses, 0 or 0.1% microbial inoculant, and 0 or 20% water were added
(Experiment 2). In large silo experiment crab waste and wheat straw (1:1)
were mixed with 20% dry molasses, 20% dry molasses and 0.1% microbial
inoculant and 16% acetic acid. In “Experiment 1” trimethylamine content
(TMA) was lower up to 8.0-19.0% dry matter for molasses and inoculant
treated silages at mixtures without added molasses or acid. In “Experiment
2” concentrations of volatile fatty acids (VFA), acetic, propionic, and
isobutyric acid were higher in mixtures with added water and molasses,
while addition of 10-20% dry molasses to crab-straw mixtures before
ensiling resulted in substantial amounts of lactic acid. In large silo
experiments treated silages with 20% molasses and 0.1% inoculant had
higher lactic acid concentration (12.76% dry matter).
Effl uent from a recirculation aquaculture system, inoculum and 0-8g/l
sodium acetate (organic carbon supplementation) were added to two
bacteria reactors, which were operated at different HRT (1-11 h). The
results showed that 90% of inorganic N and 80% of ortho-phosphate-P
were converted, whereas at 11, 6, 3 and 2h HRT, crude protein production
was higher than volatile suspended solids (VSS) production. Furthermore,
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